In recent years, there has been an increasing demand for analyzing big data by using a database that manages a large amount of data in units of petabytes (hereinafter, referred to as “PByte”). Because data freshness is an important factor in the analysis on such big data, there has been a demand for adding data in units of several gigabytes (hereinafter, GByte) while searching processing is in process. In this context, a method has been known in which a storing area for a data table to be newly added (hereinafter, referred to as “new data table”) is distinguished from an existing area (area for a stored data table) (For example, PTL1).
According to PTL 1, every time a new data table is input, an area different from the existing area is reserved as a storage destination of the new data table, and the new data table is stored in the reserved area.
In this method, to determine whether a target column in the new data table stored in the area satisfies a unique constraint condition (a condition for ensuring uniqueness), the target columns in the new data table need to be compared with the target columns in the stored data table in the all the existing areas (for example, PTL2).